On the radio path, both AWGN, i.e. additive white gaussian noise, and different interference signals or fading multipath-propagated signal components of different signals are summed up in the desired signal. Interferences are usually caused inadvertently by other systems or other users of the same system, but they can also be caused deliberately. There have been attempts to eliminate or attenuate interferences with for instance different coding-decoding methods, channel equalizers and filtering. However, it has been problematic to find a sufficiently efficient noise-attenuation method that would be applicable to wideband telecommunications systems. The problem has specifically been to find such a method that would efficiently attenuate also relatively wideband interference in wideband data transmission systems.
Singular value decomposition, i.e. SVD, refers to numeric signal processing applied to several objects of use, such as spectral analysis, design of filters, and reduction and estimation of model orders. Singular value decomposition can be applied directly to processing data matrices, and it is applicable to both real and complex value matrices. Singular value decomposition is described in more detail in publication by Todd K. Moon, Wynn C. Stirling: Mathematical Methods and Algorithms for Signal Processing, Prentice Hall, 2000, which is incorporated as reference herein.